Boiler



April 25, 1967 w. J. WITTEN, JR 3,315,646

BOILER Filed Jan. 22, 1965 2 Sheets-Sheet 1 INVENTOR. Wilson J. Witten, Jr.

ATTORNEY April 1957 w. J. WITTEN, JR 3,315,646

BOILER Filed Jan. 22, 1965 2 Sheets-Sheet 2 INVENTOR ATTORNEY Wilson J. WiHen, Jr.

United States Patent 3,315,646 BOILER Wilson J. Witten, in, Louisville, Ky., assignor to American Radiator & Standard Sanitary Corporation, New York, N.Y., a corporation of Delaware Filed Jan. 22, 1965, Ser. No. 427,325 Claims. (til. 122-235) This invention pertains to boilers and more particularly to boilers employed in circulating hot Water in heating systems. I

In domestic heating plants, it is desirable to have the heating plant as small and as inexpensive as possible and still supply the required quantity of heat. Most residential heating plants available today which employ combustible fuels need a separate furnace or boiler room and a chimney or flue. The boiler room takes away from the available living space of a home and the chimney adds to building costs. Furthermore, presently available domestic heating plant boilers and their related parts are assembled on the site by a plumber who must, in addition to making the minimum water and fuel connections, incorporate into the plant water circulators, expansion tanks, etc., which require further plumbing. Usually, because of the multiplicity of connections, a considerable amount of plumbing time is required for an installation. Furthermore, because of the size and weight of the boilers, more than one man is required during installation.

It is accordingly, a general object of the invention to provide a more compact boiler for a heating plant.

It is another object of the invention to provide a much smaller in size and lighter in weight heating plant than presently available plants especially for residential users.

It is a more specific object of the invention to provide a heating plant which does not require the usual draft diverters and exhaust systems such as chimneys.

Briefly, the invention contemplates a boiler which comprises a hollow cylindrical burner of porous refractory cloth having an open and a closed end. A heat exchanger which includes a plurality of hollow tubes is supported by header means so that the tubes are parallel to the axis of the burner and circumferentially surround it. The header means also conduitly connects the tubes to a circulating water system. Means feed a combustible gas-air mixture under pressure to the open end of the burner. Therefore, when the gas-air mixture passes through the cloth and is ignited, it burns on the outside surface of the cloth. The heat generated by the burning fuel is absorbed by the heat exchanger and transferred to the circulating water of the system.

A feature of the invention resides in the fuel feed means and includes a venturi gas-air mixer to insure that the proper mixture of combustible gas and air is always fed to the burner.

Another feature of the invention is concerned with the guiding of the combustion products in the form of hot gases about the heat exchanger and with the exhausting of these gases.

A further feature of the invention concerns the safe operation of the boiler and provides for the presence of a particular type of heat sensor in a particular region of the boiler so that fast thermal response is obtained.

Yet another feature of the invention is directed to the provision of a pre-packaged boiler plant requiring a minimum of installation time.

Other objects, features and the advantages of the invention will be apparent from the following detailed description when read with the accompanying drawings which show, by way of example and not limitation, the now preferred embodiment of the invention.

In the drawings:

3,315,646 Patented Apr. 25, 1957 FIG. 1 shows a side view of a boiler with its jacket removed, in accordance with the invention;

FIG. 2 is a top view of the boiler of FIG. 1;

FIG. 3 is an end view of the boiler of FIG. 1 showing the boiler with a jacket which is partially broken away; and

FIG. 4 shows the details of the heat exchanger, burner and cylindrical enclosure of the boiler of FIG. 1.

Referring now to FIGS. 1, 2 and 3, a boiler according to the invention, is shown comprising a frame 10 encased by a boiler jacket 12. The frame supports, in known manner, a burner-heat exchanger unit 14 encased in a cylindrical housing 16; a fuel feed system 18; and a circulating water system 20. Generally, the fuel feed system 18 feeds a combustible gas-air mixture to the burner-heat exchanger unit 14 where the mixture burns creating heat and gaseous wastes. The gaseous wastes exit via the end 22 of cylindrical housing 16. The heat is transferred through the agency of heat exchanger portion of unit 14 to water forced to circulate by the circulating water system 20 which is connected to radiators or the like.

More particularly, unit 14 (see FIG. 4) comprises a hollow cylindrical burner 24 of porous refractory cloth surrounded and supported by heat exchanger 26. Burner 24 has an open end 27 and a closed end remote therefrom. The detailed construction of burner 24 is fully disclosed in copending application Ser. No. 397,747, filed Sept. 21, 1964.

Heat exchanger 26 comprises a plurality of finned hollow tubes 28 circumferentially disposed in mutually parallel relationship about burner 24. First ends of each of the tubes 28 are connected to a floating interconnecting header 30. Header 31) includes an internal chamber or fluid passageway so that the first ends of tubes 28 are conduitly connected. Header 30 includes a central portion (not shown) for supporting the closed end of burner 28. The second ends of each of the tubes 28 are connected to an inlet-outlet header 32 which includes a fluid inlet 34 and a fiuid outlet 36. Header 32 is a hollow toroid including a diametral partition dividing the inner chamber into an inlet region conduitly connected to fluid outlet 36. The second ends of half of the tubes 28 are connected to the inlet region; and the second ends of the other half of the tubes 28 are connected to the outlet region. Accordingly, when fluid such as water is pumped into fluid inlet 34, it travels down one half of the tubes 28 to interconnecting header 30 and back through the other half of the tubes 28 to fluid outlet 36. The inner surface 38 of header 32 supports the open end 26 of burner 24. Further details of the construction of heat exchanger 26 may be found in the copending application.

The fuel feed system 18 comprises a centrifugal blower 40 driven by motor 42. The blower 40 has an air inlet covered by an air filter 44 and a pressurized air outlet 46. The outlet 46 is connected to a pressure inlet of venturi gas-air mixer 48. Mixer 48 has a throat inlet 52 connected via conduit 54 to an automatic gas valve 56 and a gas pressure regulator 58. The inlet of regulator 58 is connected via gas inlet conduit 60 which passes through an opening of the jacket 12 to a pressurized gas line (not shown). Mixer 48 includes an outlet 62 coupled via conduit 64 to the open end of burner 24.

In the operation, pressurized combustible gas from a public utility source is fed via inlet 60 to a gas pressure regulator 58. The gas pressure is dropped by regulator 58 to substantially atmospheric pressure and fed via valve 55 to throat inlet 52 of venturi gas-air mixer 48. At the same time, pressurized air is pumped into the pressure inlet 50 of mixer 48. Accordingly, by virtue of the Bernoulli effect, gas is sucked into the mixer 48 where it is mixed with the air from blower 40 to form a combustible gas-air mixture that is fed via conduit 64 to the central portion of burner 24. The combustible gas-air mixture diffuses through the porous cloth thereof and after ignition by a spark plug (not shown) burns on the outer surface of burner 24. The hot combustion product gases flow radially through the spaces in finned tubes 28 to the region between the outer periphery of heat exchanger 26 and the inner surface of cylindrical enclosure 16 (FIG. 4), The waste gases then flow out the end of cylindrical enclosure 16 which passes through jacket 12. said end acts as a flue pipe carrying away the exhaust gases.

It should be noted that such an arrangement of a cylindrical enclosure surrounding a plurality of circumferentially arrayed finned tubes encompassing a porous cloth burner provides ample heat transfer surface for good efficiency and low pressure drop, thus easing the requirements for the blower.

It should also be noted that the combination of the venturi gas-air mixer and the gas pressure regulator provide means for proportioning the combustible gas flow with respect to the air flow. With such a combination, the quantity of combustible gas drawn into the system is directly related to the quantity of air forced into the system by the blower. Hence, the ratio of gas to air in the mixture will remain constant even when there is clogging of the filter 44 or variation in the capacity of blower 40. In fact, if blower motor 42 fails, no gas will be sucked from valve 56 by the mixer 48.

Of course, it is apparent that louvres are provided in jacket 12 to insure an adequate quantity of air for blower 40.

The circulating water system 20 will now be described. Water is drawn into the boiler via inlet pipe 7 under the influence of motor driven circulator 72 to the fluid inlet 34 of heat exchanger 14; and Water is forced out to the radiators from fluid outlet 36 via outlet pipe 74. A pressurized-diaphram expansion tank 76 is connected to the vertical section of the outlet piping 74 by pipe threaded means 75. Conduit means also connect an automatic air vent means 73 to tank 76. In outlet pipe 74 there is a relief valve for connecting outlet pipe 74 to a relief overflow pipe.

It should be noted that the circulator 72 and the expansion tank 76 are within the jacket 12; and as far as the circulating water system is concerned only three pipes pass through jacket 12, i.e., inlet pipe 70 and outlet pipe 74 and a relief overflow pipe.

Although the control system for the boiler is fully described in copending application, several control features are worth noting. In particular, because of the low water content of the unit, boiler water temperature would increase at a rate of five degrees per second if the circulator were to fail. Accordingly, a quick action thermistor 37 is installed through a threaded opening in the outlet side of header 32. The thermistor 37 is connected via lead 39 to control unit 84. Control unit 84 is connected via leads 86 to automatic gas valve 56. In operation, when the boiler water temperature exceeds say 250 F., control unit 84 feeds signals via leads 86 to automatic gas valve .56 to close the valving mechanism therein. A flame sensor 80 comprising a cadmium sulfide cell in a finned radiator passes through housing 16 to sense for flame on burner 24. Signal lead 82 connects flame sensor 80 to control unit 84. Generally, whenever no flame is sensed automatic gas valve 56 cuts off the flow of gas to the burner.

There has thus been shown an improved boiler for home heating plants which, by virtue of the burner-heat exchanger configuration in combination with a pressure fuel feeding system, is very compact and efficient. In fact, a working embodiment of the invention weighs about 100 lbs. and occupies about 4 cubic feet, and is rated at 90,000 Btu. input With an efliciency of greater than 80%.

Furthermore, since there are only three water line connections, one gas line connection and a single electrical input, and since the circulator and expansion tank are within the boiler jacket a single plumber can install the unit in about a half hour.

In addition, by virtue of the pressurized combustion system, no draft diverter or chimney is required. In fact, the end of the enclosure projecting through the boiler jacket may be fitted directly through a building wall.

While only one embodiment of the invention has been shown and described in detail, there will now be obvious to those skilled in the art many modifications and variations which satisfy many or all of the objects of the invention. However, these modifications and variations will not depart from the spirit of the invention as defined by the appended claims.

What is claimed is:

1. A boiler comprising: a hollow cylindrical burner of porous refractory cloth including an open and a closed end; a heat exchanger including a plurality of mutually parallel finned hollow tubes circumferentially disposed about said burner, an interconnecting header means connected to the first ends of said tubes and including a fluid passageway for providing a fluid path from a first group of said tubes to a second group of said tubes, and an inletoutlet header means connected to the second ends of said tubes, said inlet-outlet header means including a fluid inlet, a fluid outlet and partition means so that said first group of said tubes is conduitly connected to said fluid inlet and said second group of said tubes is conduitly connected to said fluid inlet and said second group of said tubes is conduitly connected to said fluid outlet; a cylindrical enclosure coaxially disposed about said heat exchanger and extending axially beyond the latter to provide an exhaust flue; means for feeding a combustible gas-air mixture under pressure to the open end of said burner; and a boiler jacket enclosing said burner, said heat exchanger, said cylindrical enclosure and said feeding means, said boiler jacket being provided with openings for conduit access to the fluid inlet and fluid outlet of said inlet-outlet header and for conduit access to said feeding means, and a further opening through which extends the portion of said cylindrical enclosure extending beyond said heat exchanger.

2. The boiler of claim 1 further comprising an expansion tank conduitly connected to said inlet-outlet header and disposed within said jacket.

3. The boiler of claim 1 further comprising a fluid circulator conduitly connected to said inlet-outlet header and disposed within said jacket.

4. The boiler of claim 1 further comprising an expansion tank conduitly connected to said inlet-outlet header and disposed within said jacket and a fluid circulator conduitly connected to said inlet-outlet header and disposed within said jacket.

5. A boiler comprising: a hollow cylindrical burner of porous refractory cloth, including an open and a closed end; a heat exchanger including a plurality of hollow tubes, and header means for supporting said tubes parallel to the axis of said burner and circumferentially around said burner and adapted to be connected to a circulating fluid system; a cylindrical enclosure coaxially disposed about said heat exchanger and extending axially beyond the latter to provide an exhaust flue; a thermistor means in said header means so as to be in intimate contact with the circulating fluid for sensing the temperature thereof; means for feeding a combustible gas-air mixture under pressure to the open end of said burner; and means responsive to said thermistor means for controlling said feeding means to stop operating when the temperature of said circulating fluid exceeds a given value.

6. A boiler comprising: a hollow cylindrical burner of porous refractory cloth including an open and a closed end; a heat exchanger including a plurality of mutually parallel finned hollow tubes circumferentially disposed about said burner, an interconnecting header means connected to the first ends of said tubes and including a fluid passageway for providing a fluid path from a first group of said tubes to a second group of said tubes, and an inletoutlet header means connected to the second ends of said tubes, said inlet-outlet header means including a fluid inlet, a fluid outlet and partition means so that said first group of said tubes is conduitly connected to said fluid inlet and said second group of said tubes is conduitly connected to said fluid outlet; a cylindrical enclosure coaxially disposed about said heat exchanger and extending axially beyond the latter to provide an exhaust flue; means for feeding a combustible gas-air mixture under pressure to the open end of said burner comprising an air blower including an inlet and an outlet for delivering air under pressure, a venturi gas-air mixer including a pressure inlet connected to the outlet of said air blower, an outlet connected to the open end of said burner, and a throat inlet adapted to be connected to a source of combustible gas; and a boiler jacket enclosing said bumer, said heat exchanger, said cylindrical enclosure and said feeding means, said boiler jacket being provided with openings for conduit access to the fluid inlet and fluid outlet of said inletoutlet header and for conduit access to said feeding means, and a further opening through which extends the portion of said cylindrical enclosure extending beyond said heat exchanger.

7. A boiler comprising: a hollow cylindrical burner of porous refractory cloth including an open and a closed end; a heat exchanger including a plurality of mutually parallel finned hollow tubes circumferentially disposed about said burner, an interconnecting header means connected to the first ends of said tubes and including a fluid passageway for providing a fluid path from a first group of said tubes to a second group of said tubes, and an inlet outlet header means connected to the second ends of said tubes, said inlet-outlet header means including a fluid inlet, a fluid outlet and partition means so that said first group of said tubes is conduitly connected to said fluid inlet and said second group of said tubes is conduitly connected to said fluid outlet; a cylindrical enclosure coaxially disposed about said heat exchanger and extending axially beyond the latter to provide an exhaust flue; means for feeding a combustible gas-air mixture under pressure to the open end of said burner comprising an air blower including an inlet and an outlet for delivering air under pressure, a venturi gas-air mixer including a pressure inlet connected to the outlet of said air blower, an outlet connected to the open end of said burner, and a throat input, and a pressure reducing valve means including an inlet adapted to be connected to a source of pressurized combustible gas and an outlet connected to the throat inlet of said venturi gas-air mixer; and a flame sensor means extending through said cylindrical enclosure for sensing a flame on said burner and means responsive to said flame sensor for controlling said valve means to close in the absence of flame on said burner,

8. A boiler comprising: a hollow cylindrical burner of porous refractory cloth including an open and a closed end; a heat exchanger including a plurality of mutually parallel finned hollow tubes circumferentially disposed about said burner, an interconnecting header means connected to the first ends of said tubes and including a fluid passageway for providing a fluid path from a first group of said tubes to a second group of said tubes, and an inlet-outlet header means, adapted to be connected to a circulating fluid system, connected to the second ends of said tubes, said inlet-outlet header means including a fluid inlet, a fluid outlet and partition means so that said first group of said tubes is conduitly connected to said fluid inlet and said second group of said tubes is conduitly connected to said fluid outlet; a cylindrical enclosure coaxially disposed about said heat exchanger and extending axially beyond the latter to provide an exhaust flue; means for feeding a combustible gas-air mixture under pressure to the open end of said burner comprising an air blower including an inlet and an outlet for delivering air under pressure, a venturi gas-air mixer including a pressure inlet connected to the outlet of said air blower, an outlet connected to the open end of said burner and a throat input, and a pressure reducing valve mean including an inlet adapted to be connected to a source of pressurized combustible gas and an outlet connected to the throat inlet of said venturi gas-air mixer, .a thermistor means extending into the fluid outlet of said inlet-outlet header means so as to be in intimate contact with the circulating fluid for sensing the temperature thereof, means responsive to said thermistor means for controlling said valve means to close when the temperature of the circulating fluid exceeds a given value; and a boiler jacket enclosing said burner, said heat exchanger, said cylindrical enclosure and said feeding means, said boiler jacket being provided with openings for conduit access to the fluid inlet and said second group of said tubes is conduitly conconduit access to said feeding means, and a further opening through which extends the portion of said cylindrical enclosure extending beyond said heat exchanger.

9. The boiler of claim 8 further comprising an expansion tank conduitly connected to said inlet-outlet header and disposed within said jacket.

10. The boiler of claim 8 further comprising a fluid circutator conduitly connected to said inlet-outlet header and disposed within said jacket.

References Cited by the Examiner UNITED STATES PATENTS 3,110,300 11/1963 Brown et al 158 99 X 3,119,439 1/1964 Weiss 158-99 3,231,016 1/1966 Stewart et a1. 263-20 X FOREIGN PATENTS 1,368,306 6/1964 France.

CHARLES J. MYHRE, Primary Examiner. 

1. A BOILER COMPRISING: A HOLLOW CYLINDRICAL BURNER OF POROUS REFRACTORY CLOTH INCLUDING AN OPEN AND A CLOSED END; A HEAT EXCHANGER INCLUDING A PLURALITY OF MUTUALLY PARALLEL FINNED HOLLOW TUBES CIRCUMFERENTIALLY DISPOSED ABOUT SAID BURNER, AN INTERCONNECTING HEADER MEANS CONNECTED TO THE FIRST ENDS OF SAID TUBES AND INCLUDING A FLUID PASSAGEWAY FOR PROVIDING A FLUID PATH FROM A FIRST GROUP OF SAID TUBES TO A SECOND GROUP OF SAID TUBES, AND AN INLETOUTLET HEADER MEANS CONNECTED TO THE SECOND ENDS OF SAID TUBES, SAID INLET-OUTLET HEADER MEANS INCLUDING A FLUID INLET, A FLUID OUTLET AND PARTITION MEANS SO THAT SAID FIRST GROUP OF SAID TUBES IS CONDUITLY CONNECTED TO SAID FLUID INLET AND SAID SECOND GROUP OF SAID TUBES IN CONDUITLY CONNECTED TO SAID FLUID INLET AND SAID SECOND GROUP OF SAID TUBES IS CONDUITLY CONNECTED TO SAID FLUID OUTLET; A CYLINDRICAL ENCLOSURE COAXIALLY DISPOSED ABOUT SAID HEAT EXCHANGER AND EXTENDING AXIALLY BEYOND THE LATTER TO PROVIDE AN EXHAUST FLUE; MEANS FOR FEEDING A COMBUSTIBLE GAS-AIR MIXTURE UNDER PRESSURE TO THE OPEN END OF SAID BURNER; AND A BOILER JACKET ENCLOSING SAID BURNER, SAID HEAT EXCHANGER, SAID CYLINDRICAL ENCLOSURE AND SAID FEEDING MEANS, SAID BOILER JACKET BEING PROVIDED WITH OPENINGS FOR CONDUIT ACCESS TO THE FLUID INLET AND FLUID OUTLET OF SAID INLET-OUTLET HEADER AND FOR CONDUIT ACCESS TO SAID FEEDING MEANS, AND A FURTHER OPENING THROUGH WHICH EXTENDS THE PORTION OF SAID CYLINDRICAL ENCLOSURE EXTENDING BEYOND SAID HEAT EXCHANGER. 